Circuit interrupter



Patented Apr. 6, 1943 UNITED STATES PATENT QFFICE CIRCUIT INTERRUPTERPennsylvania Application January 24, 1940, Serial No. 315,306

20 Claims.

This invention relates generally to circuit interrupters, and moreparticularly to interrupters of the type adapted to be automaticallydisconnected from their associated circuit in response to aninterrupting operation.

Although my invention will be disclosed herein as embodied in a highvoltage drop-out fuse wherein it has certain particular novelcooperation and utility, it should be understood at the outset that itis also applicable to other circuit interrupters of the type capable ofautomatically interrupting a circuit in response to the passagetherethrough of currents greater than a predetermined value.

Circuit interrupters of the above type, and particularly high voltagefuses may be movably mounted adjacent one end thereof for movement intoor out of engagement with respect to a resilient line contact, and aspring-biased latch may be provided to maintain the fuse in engagementwith the resilient contact.

One object of my invention is to provide a circuit interrupter of thetype described with novel means to enable the interrupter toautomatically release itself from at least one of its associated linecontacts in response to a circuit interrupting operation.

Another object of my invention is to provide an interrupter of the typedescribed with novel means operable automatically in response to aninterrupting operation for removing the support from a part of theinterrupter which normally maintains the interrupter in its associatedcircuit.

Another object of my invention is to provide a circuit interrupterembodying relatively movable parts, together with novel means normallymaintaining said parts in fixed relation.

A further object of my invention is to provide an interrupter enclosureof novel construction.

Still another object of my invention is to provide a high voltage fusehaving embodied therewith novel means enabling the same to becomereleased from its associated circuit so that it may drop-out to insertan air gap in the circuit.

Another object of my invention is to provide in a high voltage renewablefuse having an enclosure embodying relatively movable parts, nove1 meansfor normally maintaining said parts in substantially fixed relation,which means operate automatically to normal position incident toassembly of the fuse, and, in response to blowing of the fuse, permitsrelative movement of said parts.

Another object of my invention is to provide a novel high voltage fuseconstruction having a novel end cap construction which is relativelymovable in response to blowing of said fuse.

These and other objects of my invention will become more apparent uponconsideration of the following specification of preferred embodiments ofmy invention, taken in connection with the attached drawings, in which:

Figure 1 is a side elevational view showing a fuse constructed inaccordance with my invention;

Fig. 2 is a longitudinal, sectional view of the fuse shown in Fig. l andshowing a fragment of the top latch for the fuse;

Fig. 3 is a fragmentary, longitudinal, sectional view of the upper fuseterminal cap assembly taken at right angles to the section of Fig. 2;

Fig. 4 is a transverse, sectional view taken substantially on the lineIV-IV of Fig. 3;

Fig. 5 is a perspective view of a supporting lever for the upper fuseterminal cap assembly;

Fig. 6 is a plan view of a supporting member in the fuse terminal capassembly;

Fig. 7 is a front view of a slightly modified form of supporting elementfor the fuse terminal cap assembly;

Fig. 8 is a fragmentary, longitudinal, sectional view similar to Fig. 4but showing a slightly modified form of construction;

Fig. 9 is a cross-sectional View of the upper fuse terminal cap assemblyshown in Fig. 8 and taken substantially on the line IX--IX of Fig.

'8; and

Fig. 10 is a fragmentary, longitudinal, sectional view similar to Fig. 8showing a further modified construction.

Referring to the drawings, I have shown in Fig. l, a channel supportingmember 2 for supporting spaced upper and lower insulators 4 and 6,suitably secured thereto. The lower insulator 6 includes a metallic capmember 8 which may be of any suitable conducting material such as copperor the like. The insulator cap 8 has secured thereto a downwardlyextending terminal portion ill for connection to a line conductor.Extending outwardly from the lower insulator cap 8 are spaced contactportions l2 adapted to pivotally support the lower end of a fuse H3. Thefuse includes a lower terminal ferrule it having on opposite sidesthereof outwardly projecting stop lugs I8 and trunnions 20, about whichthe fuse is adapted to pivot. Each contact leg 12 has its outer portionsubstantially U-shaped in form with a pair of indentations at each endof the bight portion thereof. The U-shaped outer portion of each contactleg I2 is provided with an upper arm 22 adapted to cooperate with thestop lug I8 and a lower guide arm 24- for guiding the trunnions into oneof the indentations in the contact legs l2. A leaf spring member 25 isfixed to the lower cap 8 between the contact portions [2, by anysuitable means such, for example, as by welding or the like, and has itsupper end bent outwardly away from the insulator cap 8 to engage anupper portion of the fuse terminal ferrulelii, to normally urge the fusein a clockwise direction about its trunnions From the foregoing, it isapparent that the fuse I4 is pivotally mounted on the lower contact arms!2 by the fuse trunnions 29, and when in a vertical position, as shownin Fig. 1, the fuse is urged by the spring 25 for pivotal'movement.

in a clockwise direction about its trunnions 20. It will be apparentthat, if the fuse is moved in this direction, it will move until thestop lugs.

B engage with the outer end of the contact arms 24, to thereby stopsuch'movement of the fuse. In this position, the fuse may be lifted outfrom between the contact arms l2 for refusing-and thereafter may beinserted between the contact arms l2 and then pivotally moved in acounter clockwise direction to the position shown in Fig.

1. Obviously, if no means is provided'for maintaining the fuse in theposition shown in Fig. 1, the fuse will necessarily move under theinfluence of spring 25 to the drop-out position in which its stop lugsl8 engage the contact arms 24.

The upper insulator 4 is also provided with a cap 26' similar to the cap8 on the lower insulator,

and the cap 26 has secured thereto an upwardlyextending terminal portion28 adapted to be con-' nected to a line conductor. Extending outwardlyfrom the upper portion of the insulator cap 28 are a pair of pivotsupporting arms 30 between which is pivotally mounted a latch 32, as bya pivot pin 34. A fixed stop -is provided slightlyspaced below the latch32 and integral with the terminal portion 23 for limiting clockwisemovement of the latch 32' about its pivot 34, for a purpose hereinafterto be described. A leaf spring 38 has I the inner end thereof fixed tothe terminal portion 28 and the outer end thereof bearing upon latch 32to normally urge the same downwardly into engagement with the fuse M, orwith the stop 38 when the fuse is not in operative position. The outerend of the latch 32 is turned upwardly,

as shown at 4B, and is provided on its underside with a notch 42 forreceiving a projection 44 on the top-of the upper fuse terminal capassembly; 66, for maintaining the fuse in the position shown in Fig. l.The fuse terminal cap assembly 46 is provided with a pair of laterallyextending spaced pivot supporting arms 43 for pivotally supporting ahook-eye operating member 5% which has an integral latch releasingextension 52 normally extending into proximity with the lower surface ofthe latch 32.

In the structure thus far described, it is apparent that, as shown inFig. 1, the fuse I4 is latched in engagement with a pair of linecontacts. The circuit through the fuse may be traced from the upper lineterminal 28, latch 32, upper fuse terminal cap assembly 45, through thefuse to the lower terminal ferrule l6, contact spring 25. to the lowerterminal lfl. To manually remove the fuse from the line contacts, it ismere- 13? necessary to insert a hook-stick or other operating memberinto the aperture in the hook-eye 5i] and exert a downward and outwardpull on the same, to thereby rotate the hook-eye in a clockwisedirection about its pivot, so that the extension 52 thereof engages thelower surface of the latch 32 to move the same upwardly out ofengagement with the projection 44 on the upper terminal cap assembly,whereupon the fuse may be rotated in a clockwise direction about itstrunnions, aided by the spring 25 on the lower terminal Hi, to theposition wherein the fuse stop lugs l8 engage the contact arms 24. Fromthis position, the fuse may be removed from the lower contact ifdesired. To re-insert the fuse in engagement with both line contacts,its trunnions 20 are first moved into engagement with the lowercontactarms I 2 and the fuse manually rotated ina counter-clockwise directionby means of the hook-eye 56, so that the projection 44 on the upperterminal fuse cap assembly engages the curved outer end 49 of the latch32 to cam the latch upwardly, and permit the projection 44 to move underthe latch to the position in which it registers with the notch 42,whereupon the latch falls downwardly into locking engagement with theprojection 44 under influence of the leaf spring 38 aided by gravity.

The fuse proper includes an insulating fuse tube 54, which may be offibre, porcelain, glass or the like, in the lower end of which ispositioned a refill element which includes an outer insulating tube 56of fibre, or the like, on the lower end of which is threadedly mounted aterminal ferrule 58 clamped in the lower fuse ferrule 16, as by theclamping ring 60, threadedly engaging the inner surface of the fuseferrule HE. A liner 62 is provided in the refill fuse tube 58 of amaterial which is capable of evolving an arc extinguishing gas when inproximity to an electric arc. The liner 62 may be of boric acid, fibre,a synthetic resin, or the like. A fusible and strain means 64 isconnected at one end, as by the screw 66, with the refill terminalferrule 58, and is connected at its other end to an arcdrawing rod 68positioned in the bore provided in the gas evolving material 62. Theupper end of the are drawing rod 68 is detachably connected with apiston member 12 slidable in the fuse tube 54, and the piston is in turnconnected to a conducting rod (4, conductively connected to the upperterminal cap assembly 46. The connection between the piston l2 and theconducting rod 14 is by way of flexible shunts l6 and further includes acoil tension spring 18 which, in the normal condition of the fuse, ismaintained .inan extended position, as seen in Fig. 2. The particularconstruction of the refill element, including the structure of aredrawing rod 68, plunger'l'l, shunts 16, and spring 18, and

the specific manner in which the refill is secured in the fuse tube andthe specific construction of these parts is substantially the same asdisclosed in the patent to H. L. Rawlins, No. 1,976,634, issued October9, 1934, and the particular fusible and strain means is particularlydisclosed and claimed in the patent to H. H. Fahnoe, 2,095,736, issuedOctober 12, 1937, with both of these patents being assigned to theassignee of this invention. Accordingly, for a more detailed descriptionof the exact construction of these parts and their method of assembly,reference is hereby made to the above-mentioned patents.

In brief, the operation of the fuse thus far described is as follows.Upon the passage of currents greater than a magnitude predetermined bythe fusible means 64, the means 64 are melted to thereby allow the coiltension spring 18 to move the piston 72 and the arc drawing rod 68upwardly within the fuse tube 54, to thereby elongate or draw outthe'arc formed by fusion of the fusible and strain means 64, intointimate engagement with the gas-evolving material 62 to therebyincrease the arc voltage and cool the arc to extinguish the same. Areleasable closure I is mounted in the lower, open end of the refillelement, and is adapted to be blown out of the lower end of the refillelement upon the occurrence of a predetermined gas pressure within thefuse.

I have shown in detail in Figs. 2 to 6 the specific construction of theupper end of the fuse which enables the same to become automaticallydisengaged from the latch 32 in response to blowing of the fuse. Theupper fuse terminal cap assembly 46, includes a sleeve portion 80 havinga lower inwardly extending flange 82 for cooperation with an outwardlyextending flange B4 on the upper end of the fuse tube 54 to limitoutward movement of the fuse terminal cap assembly 46 with respect tothe fuse tube 54. The sleeve 80 is freely slidably mounted on the fusetube 54 and packing material 86 is provided between the sleeve flange 82and the fuse tube flange 84 for a purpose to be hereinafter described.The packing material 86 is preferably a resilient material such, forexample, as rubber or the like. A cover cap 88 carrying the latchengaging projection 44 is threadedly engaged with the upper end of thesleeve 80 and with the conducting rod I4. Threadedly engaged withinternal threads provided on the sleeve 00 is a conductor rod support 90provided with a central circular aperture 92 for receiving the conductorrod I4 (Fig. 6), and

also provided with an elongated slot 94 extending therethrough forreceiving an integral pin 91 provided on the conductor rod I4. Above theslot 94, there is provided a notch in the upper surface of the support90 which provides shoulders 96 and 08 on opposite sides of the slot 94.Upwardly extending projections 99 are provided at the inner edges ofshoulders 06 and 98 adjacent the outer ends thereof for maintaining pin91 in the dotted line position shown in Fig. 6. The central portion ofthe outer ends of the upper notch are cut slightly deeper as at I00 toprovide notches for the reception of a tool for rotating the support 90for threadedly engaging or disengaging the same from the sleeve 80. Anoperating sleeve member I02 having a central opening which is substantially square in cross-section, as seen. in Figs. 3 and 4, to conform tothe cross-section of rod I4 so as to be slidably but nonrotatablymounted on the squared depending portion of the conducting rod I4. Thesliding movement of the operating member I02 is limited between thesupporting member 90 and the stop I04 mounted on the lower end of theconducting rod I4. The operating sleeve I02 has secured to its lowerend, the upper end of the coil tension spring I0, as for example, by thespring being tightly coiled in corresponding notches in the sleeve I02.Supporting levers I06 are pivotally mounted on the upper end of the fusetube 54 for supporting the upper fuse terminal cap assembly 46 in anextended position normally, with respect to the fuse tube 54. As shownin Fig. 5, each supporting lever I06 includes a pivot aperture I08, anupwardly extending laterally curved supporting arm H0, a laterallyextending actuating arm H2, and a stop lug H4 spaced from the pivotaperture I08. As shown in Figs. 2 to 4, these supporting levers I00 arepivotally mounted on pivot supporting lugs H6 provided integral with theupper end of the fuse tube and are provided with l spring H8 about 75slot 04 provided in the supporting'member 00..

iii)

the outer end of each pivot .pin which coil springs normally urge thesupporting levers in a direction to move the supporting arms I I0thereof into a position in which they are parallel with the top of thefuse; or as viewed in Fig. 3, the coil spring I I8 tends to move thesupporting lever I06 shown in Fig. 3 in a clockwise direction about itspivot aperture I08. The levers are normally prevented from moving by aflange I provided on the upper end of the operating sleeve I02 whichengages the top surfaces of the actuating arms I I 2 of the supportinglevers I06. Operating sleeve I02 is also provided with inwardlyextending opposed notches on its periphery at I22 for a purpose to behereinafter described.

In the position shown in Figs. 2 to 4, it is obvious that the tension oncoil spring I8 maintains the operating sleeve I02 in the lower positionas shown in Fig. 2, thereby maintaining the supporting levers I06through the actuating arms I I2 thereof, in a vertical position or aposition in which the supporting arms IIO are substantially vertical sothat the upper terminal cap assembly is maintained in the extendedposition shown.

When the fuse blows, as previously described, the coil spring I8operates to move the arc drawing rod 68 upwardly, and inasmuch as thespring I8 is no longer anchored at its lower end, it no longer is ableto maintain the operating sleeve I02 in the position shown in Fig. 2,whereupon the coil springs I I8 mounted on the pivot pins for thesupporting levers I06 are free to rotate their corresponding levers intoa position where the supporting arms I I0 thereof no longer act tomaintain the upper fuse terminal cap assembly I06 in the position shownin Fig. 2, whereupon the entire assembly 46 is free to slide downwardlyon the fuse tube 54, which movement is given an initial impetus by thelatch 32 under the influence of its spring 38, since the latch 32 isfree to move downwardly a slight distance before it engages its stop 36.The compressed packing material 86, likewise is available to aid ininitially moving the upper terminal assembly 46 downwardly and, underthese initial forces, the assembly 46 is moved to the position shown indotted lines in Fig. 1, aided, of course, by the force of gravity, sothat the projection 4-4 on the cover 88 of the assembly 46 is moved to aposition spaced below the latch 32 so that it is disengaged therefrom,and the leaf spring 25 on the lower insulator cap 8 is then free to movethe fuse I4 in a clockwise direction about its trunnions 20 to an openposition, such as previously described.

Having moved to such an open position. the fuse may then be removed andrefused by removing the clamping plug and the refill from the bottomsubstantially in the same manner out lined in the previously mentionedRawlins patent.

. The cover 88 for the upper terminal cap assembly 46 is then unscrewedfrom the sleeve and conductor rod I4. The conductor rod is kept fromrotating by pin 9] which normally lies in the notch in the supportingmember diagonally of the same, as shown in dotted lines, Fig. 6. The

This also causes operating sleeve I02 to rotate to bring itsperipheraInotches I22 into alignment with the operating arms H2 of the supportinglevers I66, whereupon the entire spring and shunt assembly is free tomove downwardly out of the lower end of the fuse tube 54. The reverseprocess is gone through after a new refill has been fastened to thespring and shunt piston I2. The conducting rod M is drawn upwardlythrough the fuse tube by any suitable operating rod which is adapted tobe threadedly engaged with the threaded upper end of the conducting rodI4, until the flange I26 on the operating sleeve I62 lies above theactuating arms I I2 of the supporting levers I66. The conductor rod I4is then rotated so as to bring the notches I22 in the operating sleeveflange I23 out of alignment with the actuating arms on the supportinglevers and simultaneously move the supporting pin 97 on the conductorrod 14 to a position diagonally above the slot 54, in the supportingmember 96; then when the rod M is released, spring I8 will operate tomove the operating sleeve I212 downwardly into engagement with theactuating arms H2 of the supporting lever I66, to rotate these levers toa position in which the supporting arms H9 thereof are substantiallyvertical, thereby moving the entire upper terminal cap assembly 46 to anextended position, substantially as shown in Fig. 2. The coil tensionspring I8 is, of course, stronger than the coil springs H8 so as to beable to move the supporting levers Hi6 against the bias of springs H8.In the event that the assembly 46 is not moved fully to the positionshown in Fig. 2 by spring T8, the assembly may be manually grasped andmoved outwardly to compress the packing material 86 and permit thesupporting arms H of the actuating levers I06 to be moved to a fullyvertical position, as shown in Figs. 2 to 4. The top cover 83 is thenscrewed into position and the fuse is ready to be reinserted in thecircuit in the marmer already described. It should be noted that thepacking material 66 serves the dual function of preventing the entranceof moisture or other contamination from the atmosphere into the fuse andalso serves to aid the latch 32 in imparting an initial force to themovable terminal assembly 46 downwardly, after the fuse blows.

A slightly modified form of terminal assembly supporting lever is shownin Fig. 7, wherein the v numeral I24 designates a supporting lever muchlike the lever I96 shown in Fig. 5. The lever I24 includes a supportingarm I26 like the supporting arm Iill, a laterally extending actuatingarm :28 and a stop lug I30. The lever I24 differs from the lever I06 inthat the pivot aperture I 32'thereof is positioned eccentrically withrespect to the supporting arm I26 of the lever so that the springs H8for moving the levers IDS to a non-supporting position may be eliminatedwhen a lever like the lever I24 is used in the structures shown in Figs.1 to 4 and 6. It is believed that it will be obvious that when a leversimilar to the lever I24 is provided in place of the lever I06 in a fusestructure such as that shown in Figs. 1 to 6, that it will be held inposition by the actuating sleeve I82 in the same manner as levers I68are held in place. However, when the upper terminal cap assembly 46 isurged to move downwardly following blowing of the fuse, the downwardforce on the upper end of the supporting arm I26 of the lever I24 willbe exerted eccentrically with respect to the pivot supporting apertureI32 of the lever, and thereby will tend to rotate the lever I24 aboutthe aperture I32 in a direction to move the supporting arm I26 to ahorizontal position. Thus, by"

moving the pivot aperture for the lever to a position eccentric to thesupporting arm of the lever, I may thus eliminate the spring which tendsto move the lever to a non-supporting position. Otherwise, the operationof a fuse such as shown in Figs. 1 to 4 and 6 and employing a supportlever I24 in place of the supporting lever I06 is exactly the same asthat described in connection with the embodiment shown in Figs. 1 to 4,and 6 and therefore, such operation and method of removing the fuse willnot be repeated here.

In Figs. 8 and 9 of the drawings, I have shown a slightly modifiedstructure for controlling the supporting levers I66. Inasmuch as most ofthe parts shown in this embodiment of my invention are the same as thoseshown in Figs. 1 to 6, I have employed like reference numerals todesignate like parts. The main difference in the construction shown inFigs. 8 and 9 over that previously described, is that springs I34 areprovided on the operating lever pivot pins, which springs are adapted tonormally urge the supporting levers I66 to an upright position as shownin Fig. 9, wherein the stop lugs H4 of the levers are engaged with theupper surface of the fuse tube flange 84. Also, the operating sleeve I36in this form of my invention is of slightly less extent than theoperating sleeve I92 of the first embodiment of my invention, and theupper flange I38 on the operating sleeve I36 is normally positioned toreside beneath, rather than above the actuating arms II2 of thesupporting levers I06.

In the operation of this embodiment of my invention, when the fuseblows, as previously described, the coil spring I8 operates to rapidlywithdraw the piston 12 upwardly in the tube 54, and with the kineticenergy which it gathers upon moving, it actuates the operating sleeveI36 upwardly, causing the flange I38 on the sleeve to strike theoperating arms II2 on the supporting levers I 06 with an impact, tocause rotation of the levers so that the supporting arms III thereof aremoved to a horizontal position. Thus, as viewed in Fig. 9, the impact ofthe operating sleeve I36 tends to rotate the supporting lever I86, seenin this figure, in a clockwise direction about its pivot axis. Thesprings I34, for normally maintaining or moving the supporting leversI06 so that the arms H0 thereof are in a vertical position, are maderelatively weak, in-

asmuch as the only function of these springs is to move the actuatinglevers to the positions shown in Figs. 8 and 9, when the fuse isassembled or after it is refused. The unlatching and movement of thefuse in this embodiment of my invention, out of engagement with itsassociated circuit is accomplished in the same manner as described inconnection with the first embodiment of my invention. Likewise, refusingor replacement of the refill unit is adapted to be carried out in thesame manner as described in connection with the first embodiment, exceptthat, since the actuating sleeve I36 in this embodiment of my inventionis shorter than the actuating sleeve I62 in the first describedembodiment, the flange I33 on the sleeve will be below, instead of abovethe actuating arms H2 of the supporting levers I66 when the conductingrod I4 is drawn upwardly through the supporting member to be supportedthereby. Therefore, these operations and the method of refusing will notbe repeated.

In Fig. 10, I have shown a still further modified form of supportingmeans for the upper terminal cap assembly 46. Here again, many of theparts are the same as in the previously described embodiments of myinvention, so like reference numerals are used to designate like parts.In Fig. 10, I have shown the operating levers as being replaced bytoggles, each of which includes a toggle lever I40 pivotally mounted ona lug, integral with the supporting member 90, and a toggle lever I42pivotally supported on a lug integral with the fuse tube 54. Theadjacent ends of the toggle levers I40 and I42 are pivotally connectedas shown, and one of the toggle pivots is provided with a biasing springI44 shown here, as applied to the upper toggle pivot, to normally urgethe toggle levers inwardly past dead center position. The lower toggle1evers I42 are each provided with an integral laterally extendingactuating arm I45 adapted to over-lie the flanges I38 on the operatingsleeve I36.

The operation of this embodiment of my invention is very similar to thatshown in Figs. 8 and 9. When the fuse blows, the kinetic energyaccumulated by the coil spring 18 and the parts moved thereby, deliversan impact blow to the operating sleeve I 36 which is imparted to the armI40 on the toggle levers I42 to move these levers relatively outwardlypast their dead center position so that the toggle may collapse, and theupper fuse terminal cap assembly 46 may move downwardly out ofengagement with respect to the latch 32, whereupon the fuse can move toan open position, as previously described. The spring I44 on the uppertoggle pivot, like the spring I34 described in connection with Figs. 8and 9, may be relatively weak since the only function which it mustperform is to move the toggle levers past their dead center positionswhen the fuse terminal cap assembly 46 is manually moved outwardly uponassembly of the fuse or upon renewing the refill, following blowing ofthe fuse.

It should be obvious from the foregoing that I have provided a novelform of fuse construction which will enable the fuse to automaticallyrelease itself from a latch holding it in its associated circuitfollowing blowing of the fuse. This release is accomplished by a portionof the fuse enclosure which is normally maintained in an extendedposition relative to the fuse tube so that it may engage a latch 32, butwhich is free to move inwardly with respect to the fuse tube followingblowing of the fuse to thereby become disengaged from the latch andpermit its movement under the influence of the biasing spring, such as25, to a disconnected position, with respect to its associated circuit.

This particular fuse construction has the advantages of other forms ofdrop-out fuse, and includes many others, such, for example, as theadvantage of providing a totally enclosed fuse, thus preventing entranceof moisture or other substances which may be deleterious to the fuse, orgas-evolving material, to the interior of the fuse. Furthermore, itshould be noted that this device cannot become released from the circuituntil the are formed by blowing of the fuse is the fuse tube. This gasunder pressure can pass between actuating sleeve I02 or I36 and the fusetube to build up pressure in can assembly 46 tending to maintain theupper terminal cap assembly 46 in its normal position until the arc isextinguished, and no more gas is evolved, whereupon the movable terminalassembly 46 is then free to move downwardly to become released from thelatch 32 and permit the fuse to move out of its associated circuit. Inother Words, the gas pressure developed by an arc tends to hold the fusein circuit rather than to accelcrate its disengagement from the circuit.

Having described preferred embodiments of my invention in accordancewith the patent statutes, I desire that it be not limited to theparticular structures disclosed herein, inasmuch as it will be obvious,particularly to persons skilled in the art, that many changes andmodifications may be made in these particular structures Withoutdeparting from the broad spirit and scope of my invention. Therefore, Idesire that my invention be interpreted as broadly as possible, and thatit be limited only by what is expressly stated in the following claims.

I claim as my invention:

1. In a circuit interrupter, an interrupter support embodying relativelymovable parts, means on said support for automatically interrupting anelectric circuit upon the passage therethrough of currents greater thana predetermined value, means normally maintaining said relativelymovable parts in extended partially overlapping relation, and saidlast-mentioned means being operable in response to an interruptingoperation of said interrupting means to permit relative inward movementof said parts toward a more completely overlapped position.

2. In a circuit interrupter, an interrupter enclosure embodyingrelatively movable parts, means on said enclosure for automaticallyinterrupting an electric circuit upon the passage therethrough ofcurrents greater than a predetermined value, means normally maintainingsaid relatively movable parts in extended partially overlappingrelation, and said last-mentioned means being operable in response to aninterrupting operation of said interrupting means to permit relativeinward movement of said parts toward a more completely overlappedposition.

3. In a circuit interrupter, an interrupter, a tubular support having anend closure slidably mounted on one end thereof, means in said supportfor automatically interrupting an electric circuit upon the passagetherethrough of currents greater than a predetermined value, meansnormally maintaining said closure in an extended closed position withrespect to said support, said last-mentioned means being operable inresponse to an interrupting operation of said interrupting means topermit said closure to move inwardly of said extended position.

4. In a circuit interrupter, an interrupter, a tubular support having anend closure slidably mounted on one end thereof, stop means includingresilient means for limiting outward movement of said closure relativeto said support, means in said support for automatically interrupting anelectric circuit upon the passage therethrough of currents greater thana predetermined value, closure supporting means normally maintainingsaid closure in engagement with said stop means with said resilientmeans i in stressed condition, and said closure supporting means beingoperable to a non-supporting condition in response to an interruptingoperation of said interrupting means, to permitinward movement of saidclosure member relative to said tubular support.

5. In a high voltage fuse, a fuse tube having an end cap slidablymounted at one end thereof, pivoted supporting means adapted in oneposition thereof to maintain said cap in an extended position withrespect to said fuse tube, means including a fusible element in saidfuse tube and extending into cooperative relation with respect to saidpivoted supporting means, whereby blowing of said fusible elementeffects movement of said pivoted supporting means to a non-supportingposition with respect to said cap.

6. In a high voltage fuse, a fuse tube having an end cap slidablymounted at one end thereof, pivoted supporting means on at least one ofsaid members, means including a fusible connection for normallymaintaining said supporting means in a position to prevent inwardmovement of said cap with respect to said tube, said supporting meansbeing biased for movement to a nonsupporting position, whereby when saidfusible connection blows, said cap is free to move inwardly with respectto said fuse tube.

7. In a circuit interrupter, a tubular casing, means in said casing forautomatically interrupting the circuit in response to the passagetherethrough of currents greater than a prede-i termined value, saidcasing including telescoping parts normally maintained in partiallytelescoped extended relation, and means responsive to an interruptingoperation of said interrupting means for permitting inward telescopingmovement of said casing parts.

8. In a circuit interrupter, a tubular casing, means in said casing forautomatically interrupting the circuit in response to the passagetherethrough of currents greater than a predetermined value, said casingincluding longitudinally movable parts, supporting means movably mountedon one of said parts and biased to a position for preventing inwardmovement of said parts, and means controlled by said interrupting meansin response to an interrupting operation thereof to move said supportingmeans to a non-supporting position to permit inward movement of saidcasing parts.

9. In a circuit interrupter, a tubular casing, means in said casing forautomatically interrupting the circuit in response to the passagetherethrough of currents greater than a'predetermined value, said casingincluding longitudinally movable parts, supporting toggle means fornormally maintaining said parts in an extended position, and meanscontrolled by said interrupting means in response to an interruptingoperation thereof to cause said toggle to collapse and permit inwardmovement of said casing parts.

10. In a circuit interrupter, a tubular interrupter casing movablymounted adjacent one end for movement of a terminal portion adjacent itsother end into and out of engagement with a cooperating contact, latchmeans adjacent said contact for latching said interrupter terminalportion in engagement with said contact, relatively longitudinallymovable latch engaging means carried by said casing and normallymaintained in an extended position beyond said casing for engagementwith said latch means, means in said casing for automaticallyinterrupting the circuit in response to the passage therethrough ofcurrents above a predetermined magnitude,

and-means controlled by said interrupting means "in response to aninterrupting operation there- -of,- for permitting inward-movement of'said latch engaging means" 'to' become disengaged from said latchmeans, to thereby permit said 'casing'terminal to move out of engagementwith respect to said contact.

11. In a'circuit interrupter, a tubular interrupter casing movablymounted adjacent one end for movement of a'terminal portion adjacent itsother end into and out of engagement with a cooperating contact, latchmeans adjacent said contact for latching said interrupter terminal inengagement withsaidcontact, a slidable cap for said other end of saidcasing normally maintained in an extended position relative to saidcasing for engagement'with said latch means, means in said casing'for'automatically interrupting the circuit'in response to the passagetherethrough of currents above a predetermined magnitude, and meanscontrolled by said interrupting means in response to an interruptingoperation thereof, for permitting inward movement of said cap away fromsaid latch means, whereby saidcasing may move to disengage its terminalfrom said contact.

12. In' a circuit interrupter, a tubular interrupter casingmovably'mounted' adjacent one end for movement of a terminal portionadjacent its other end into and out of engagement with a cooperatingcontact, latch means adjacent said contact for latching said interrupterterminal in engagement with said contact, a slidable 'cap for said otherend of said casing normally maintained in" an extended position relativeto said casing for engagement with said latch means, means in' saidcasing for automatically interrupting the circuit in response to thepassage therethrough of currents above apredetermined magnitude, andmeans controlled by said interrupting means in response to aninterrupting operation thereof, 'for'permitting inward movement of saidcap away from said latch means, whereby said casing may move todisengage its terminal from said contact, said latch means being biasedfor limited movement in the direction of inward movement'of said cap,whereby to impart an initial impetus to such movement of the cap.

13. In a renewable'fuse, an elongated fuse tube, a fuse refill unitadapted to be inserted in one end of [said tube, andreleasably securedtherein, said refill unit including a fusible element and a pair of fuseterminals, a terminal cap structure slidably mounted on the other'end ofsaid fuse tube, saidcap structure'including a removable end wall'portionadapted to be removably secured to said'cap structure and to an inwardlyextending conducting portion, which is in turn conductively andresiliently connected to one of said fuse terminals, means-coactingbetween said fuse tube'and cap structure to normally maintain said capstructure in an'extended position relative to said tube, means slidablymounted on said conducting portion for actuating said cap supportingmeans in responseto blowing of said fusible element to permit said capto move inwardly relativeto said fuse tube, means in said cap structurefor supporting said conducting portion when said end wall portion isremoved y'and said means being constructed and arranged so thatsaidconducting portion and actuating'means are removable as a-unit withsaidconnection to said one fuse terminal,

from one end of saidfuse tube.

14. In a renewable fuse, an elongated fuse tube, a fuse refill unitadapted to be inserted in one end of said tube, and releasably securedtherein, said refill unit including a fusible element and a pair of fuseterminals, a terminal cap structure slidably mounted on the other end ofsaid fuse tube, said cap structure including a removable end wallportion adapted to be removably secured to said cap structure and to aninwardly extending conducting portion, which is in turn conductively andresiliently connected to one of said fuse terminals, means coactingbetween said fuse tube and cap structure to normally maintain said capstructure in an extended position relative to said tube, means slidablymounted on said conducting portion, outwardly of said cap supportingmeans for actuating the same in response to blowing of said fusibleelement to permit said cap to move inwardly relative to said fuse tube,means in said cap structure for supporting said conducting portion whensaid end wall portion is removed, and said means being constructed andarranged so that said conducting portion and actuating means areremovable as a unit with said connection to said one fuse terminal, fromsaid one end of said fuse tube.

15. In a circuit interrupter, a tubular interrupter casing movablymounted adjacent one end for movement of a terminal portion adjacent itsother end into and out of engagement with a cooperating contact, latchmeans adjacent said contact for latching said interrupter terminal inengagement with said contact, said casing embodying telescoping partsone of which is engageable by said latch means when in a normal extendedposition partially telescoped, means in said casing for automaticallyinterrupting the circuit in response to the passage therethrough ofcurrents above a predetermined magnitude, means controlled by saidinterrupting means in response to an interrupting operation thereof, forpermitting inward movement of said latch engaging part to a more fullytelescoped position so as to become disengaged from said latch means,and said latch engaging part having a closed end, whereby pressuresdeveloped by an arc in said casing will tend to prevent release of saidlatch means until said arc is extinguished.

16. In a fuse, a fuse tube, fusible means in said tube, means of amaterial capable of evolving an arc extinguishing gas when in proximityto an electric are forming a restricted arc passage in said tube,resilient means biasing one terminal of said fusible means for movementthrough said passage upon fusion of said fusible means to draw out andextinguish the resulting arc, means slidably mounted with respect tosaid tube, means normally supporting said slidable means in an extendedposition with respect to said tube, and said last mentioned meanspositioned to be engaged by a part movable with said resilient meansadjacent the end of said arc drawing movement to release said slidablemeans for inward movement with respect to said tube.

17. In a fuse, a fuse tube, fusible means in said tube, means of amaterial capable of evolving an arc extinguishing gas when in proximityto an electric are forming a restricted arc passage in said tube,resilient means biasing one terminal of said fusible means for movementthrough said passage upon fusion of said fusible means to draw out andextinguish the resulting arc, means slidably mounted with respect tosaid tube, means pivotally mounted on said tube and normally engagingand supporting said slidable means in an extended position with respectto said tube, and said last mentioned means positioned to be engaged bya part movable with said resilient means adjacent the end of said aredrawing movement to pivotally move said supporting means to anon-supporting position and thereby release said slidable means forinward movement with respect to said tube.

18. In a fuse, a fuse tube, fusible means in said tube, means of amaterial capable of evolving an arc extinguishing gas when in proximityto an electric are forming a restricted arc passage in said tube,resilient means biasing one terminal of said fusible means for movementthrough said passage upon fusion of said fusible means to draw out andextinguish the resulting arc, means slidably mounted with respect tosaid tube, means pivotally mounted on said tube and normally supportingsaid slidable means in an extended position with respect to said tube,means biasing said supporting means to said supporting position, andsaid supporting means positioned to be engaged by a part movable withsaid resilient means adjacent the end of said are drawing movement torelease said slidable means for inward movement with respect to saidtube.

19. In a fuse, a fuse tube, fusible means in said tube, means of amaterial capable of evolving an arc extinguishing gas when in proximityto an electric are forming a restricted arc passage in said tube,resilient means biasing one terminal of said fusible means for movementthrough said passage upon fusion of said fusible means to draw out andextinguish the resulting are, means slidably mounted with respect tosaid tube, means pivotally mounted on said tube and normally supportingsaid slidable means in an extended position with respect to said tube,means biasing said supporting means to a non-supporting position, andsaid resilient means engaging said supporting means to normally maintainsaid supporting means in said supporting position, whereby upon fusionof said fusible means said supporting means is released for pivotalmovement under the influence of said biasing means to a non-supportingposition to permit inward movement of said slidable means with respectto said tube.

20. In a fuse, a fuse tube, fusible means in said tube, means of amaterial capable of evolving an arc-extinguishing gas when in proximityto an electric are forming a restricted arc passage in said tube,resilient means biasing one terminal of said fusible means for movementthrough said passage upon fusion of said fusible means to draw out andextinguish the resulting are, an end cap slidably mounted with respectto said tube, means normally supporting said end cap in an extendedposition with respect to said tube, and said last-mentioned meanspositioned to be engaged by a part movable with said resilient meansadjacent the end of said are drawmg movement to release said end cap forinward movement with respect to said tube.

JAMES M. WALLACE.

